#include <algorithm>
#include <cmath>
#include <cstdio>
#include <cstring>
#include <deque>
#include <iostream>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <utility>
#include <vector>
#define p(s) cout<<(s)<<endl
#define REP(i,n,N) for(int i=n;i<N;i++)
#define RREP(i,n,N) for(int i=N-1;i>=n;i--)
#define CK(n,a,b) ((a)<=(n)&&(n)<(b))
#define F first
#define S second
typedef long long ll;
using namespace std;

ll N,ans;

int main(){
    cin>>N;
    if(N%2) ans=N;
    else ans=N/2;
    for(ll i=3;i*i<=N;i++){
        if(N%i==0){
            ans=i;
            break;
        }
    }

    p(ans);
    return 0;
}